There were two different stories floating around the internet last week—each one startling in its own right, and both highlighting the ups and downs in the search for alien life.
First, after Curiosity drilled into a rock on Mars, scientists declared that in a long-ago epoch of Martian history, the Red Planet had an environment that very well could have supported life. Just as intriguing was an article written by Charles Cockell, the director of the U.K. Center for Astrobiology at the University of Edinburgh, who said that “although habitable alien planets might abound in solar systems around the universe, it does not mean these locales harbor extraterrestrial life.” His theory is that alien life may be rare across the universe, if it even exists at all.
One of those holds a glass-half-full outlook for the possibility of extraterrestrial life, and the other is distinctly half-empty.
So, what are we to make of this?
The latest discovery on Mars is just one more piece in the cosmic puzzle that indicates life in our galaxy may be plentiful. New theories suggest that as many as a billion Earth-type planets may exist in our galaxy and that the star nearest our own may have a planetary system as well. We know the same process that made our planet happens throughout the galaxy, and the same elements that made life possible here exist in much of the universe. It’s now also thought that even brown dwarfs may have planetary systems around them suitable for some forms of life. And if that’s not enough, the recent discovery of sucrose (more commonly known as sugar and also an important ingredient for life) was discovered around a star 400 light-years away.
Cockell’s theory is that life on Earth is just a random series of events which may have happened totally by accident, and that the odds of it occurring again somewhere else are long indeed. If there were only a million or so stars out there, we could concede he might have a point—but there aren’t. There are about 200 billion stars in our galaxy, many of which have planetary systems containing at least one world or more that could be habitable—that’s a staggeringly large number. And the odds are highly unlikely that, in all that cosmic real estate, we are the only game in town.
Given that life has appeared on one world in our solar system and quite possibly has existed on a second—in essence, if we found multiple instances where life emerged within a single solar system—it would virtually guarantee that this process has taken place repeatedly throughout the cosmos.
Intelligent life … now that may be another story.
Many scientists think SETI’s (Search for Extraterrestrial Intelligence) lack of success after 50 years of searching is further proof that Cockell is right, but this lack of evidence could be due to a combination of other mitigating factors. Because of the vast number of stars out there, and the potential radio frequencies a civilization might be broadcasting on, only when more powerful telescopes come online do we have a chance of detecting them. Even then it still might be difficult, because our rapidly advancing technology, our satellite TVs, and the digital revolution are soon to render our planet into what Frank Drake describes as “invisible” to aliens—at least in the radio spectrum.
Noted British astronomer Sir Martin Rees suggests aliens may be using entirely different forms of communication, such as neutrinos or gravitational waves, or methods we can’t even fathom. The late Arthur C. Clarke summed it up best when he said, “The fact that we have not yet found the slightest evidence for life … much less intelligence … beyond this Earth does not surprise or disappoint me in the least. Our technology must still be laughably primitive, and we may be like jungle savages listening for the throbbing of tom toms while the ether around them carries more words per second than they could utter in a lifetime.”
Fermi’s Paradox basically says if advanced aliens are out there, then we should have seen evidence of them by now. But perhaps there is another way of looking at it. Because the majority of stars are considerably older than ours, aliens should be far more advanced than us—and keep in mind we are not talking about our TV and movie aliens that are, at the most, two hundred years or so further along. We are talking probably thousands of years. And if that’s true, surely they must have long ago developed the sensitive instruments required to bridge the vast distances between the stars and detect our presence. Which means they know we’re here. So, why haven’t they dropped by? There could be many reasons. One favored by some is that intelligent life in our galaxy is abundant enough, but we are just too primitive to make the long trip to our remote little spot on the galaxy’s spiral arm worthwhile to them. There are probably many far more interesting and much closer places for them to go.
The only question that really is left: just how pervasive is intelligent life? Probably more than a lot of us think, but not as much as we would have hoped. A conservative guess would put that number at about 2,000 in our galaxy. Now that may sound like a large number, but it’s really not. If there are 200 billion stars in our galaxy, then only .00001 percent of all stars have an intelligent civilization orbiting around them. Or to put it another way, one out of every 100 million stars probably has a world with intelligent beings living on it.
So which is it—a lot or a little?
That depends on your point of view.
As mentioned earlier, there are worlds within our own galactic backyard which we could find life on in fairly short order. How soon? Within 5-7 years from now we could discover compelling evidence that life exists in our solar system. The prime locations being underground on Mars, deep within the oceans of Europa, or possibly Enceladus.
Within 10-15 years we should have developed sophisticated enough telescopes to image exoplanets directly and analyze the spectral signature of their atmospheres. At this point we could discover compelling evidence that life exists outside our solar system on one of the many planets or moons that exist in the Milky Way.
What about 15-20 years from now? We may very well have detected a signal or been able to observe some type of compelling evidence that intelligent life exists in our galaxy. This will not only rewrite the textbooks, but also fundamentally alter the way we feel about ourselves and our place in the universe.